Conditions of the neck or upper thoracic spine may cause referred pain to the shoulder. The comprehensive evaluation of shoulder pain includes careful examination of the cervical and thoracic spine.
1. Impingement Syndrome, Rotator Cuff Tendinosis or Tears, Supraspinatus Tendinitis, Subacromial Bursitis
The term impingement syndrome has replaced more diffuse diagnostic terms such as bursitis and tendonitis in the definition of shoulder pain following either repeated overuse or sudden overload. This pathology accounts for most shoulder pain that occurs spontaneously or with occupational loads.
In the normal shoulder, the coracoacromial ligament crosses the supraspinatus tendon of the rotator cuff. In some individuals, when a hand is brought from the side to an overhead position in forward flexion or abduction, there may be contact pressure or impingement of the acromion and coracoacromial ligament on the rotator cuff or the intervening bursa. The pathology starts with a subacromial bursitis and may progress to an irritation of the supraspinatus tendon or tendonitis. Further progression leads to the beginning of ulceration (partial-thickness tear) of the tendon, which can lead to a full-thickness discontinuity or rupture of the rotator cuff. The long head of the biceps projecting across the joint beneath the cuff to its origin on the supraglenoid tubercle may be damaged. Paralleling these soft-tissue changes, the anteroinferior aspect of the acromion develops osteophytic lipping with further encroachment on the subacromial space.
The onset of anterior shoulder pain may be gradual or acute. Occasionally, the onset coincides with the start of new repetitive-motion work activities, especially overhead work. Patients may be unaware of the inciting activity. The pain may be expressed generally over some aspect of the anterior shoulder. In some cases, pain is limited to the lateral arm about the deltoid insertion on the humerus. Occasionally, pain is referred to the distal arm, elbow, and rarely, to the hand.
All levels of pain occur, including severe pain at rest caused by a tense subacromial bursa. Night pain is a common complaint that brings the patient to medical treatment.
Posttraumatic impingement syndrome may occur after a minor injury to the arm or shoulder. The self-imposed immobilization of the shoulder predisposes the patient to the impingement syndrome because of imbalanced rotator cuff muscle function secondary to painful inhibition of normal motion.
On physical examination, patients begin to experience anterior shoulder pain when the arm is abducted to 30–40 degrees or flexed forward to 90 degrees or more. With the elbow flexed at 90 degrees, active external rotation usually does not cause discomfort. However, internal rotation (when the patient attempts to place his or her thumb on the opposite inferior angle of the scapula) is painful. With significant disruption of the rotator cuff, a patient may have no active elevation past 90 degrees of flexion or weakness ...